WO2012118270A1 - Method and apparatus for searching control information by terminal in multi-node system - Google Patents

Abstract

Provided are a method and an apparatus for searching control information by a terminal. The method comprises the steps of: acquiring from a base station, by means of a physical downlink control channel (PDCCH) or an upper layer message, at least one type of information being from location information on a physical control format indication channel (E-PCFICH) or location information on an E-control region; receiving the E-PCFICH based on the E-PCFICH location information; acquiring size information on the E-control region by means of the E-PCFICH; and searching E-PDCCH in the E-control region.

Description

Method and apparatus for retrieving control information of terminal in multi-node system

The present invention relates to wireless communication, and more particularly, to a method and apparatus for retrieving control information of a terminal in a multi-node system.

Recently, data transmission volume of wireless communication networks is increasing rapidly. This is due to the advent and widespread adoption of various devices, including machine-to-machine (M2M) communications and smartphones and tablet PCs that require high data throughput. Carrier aggregation (CA) technology, cognitive radio (CR) technology, etc., which efficiently use more frequency bands to meet the high data rates required.Multi-antenna technology to increase data capacity within limited frequencies. In recent years, multi-base station cooperative transmission technology has emerged.

In addition, wireless communication networks are evolving toward increasing densities of nodes that can be accessed around users. Here, the node may mean an antenna or a group of antennas separated by a predetermined interval from a distributed antenna system (DAS), but may be used in a broader sense without being limited to this meaning. That is, the node may be a macro base station, a picocell base station (PeNB), a home base station (HeNB), a remote radio head (RRH), a remote radio unit (RRU), a repeater, a distributed antenna (group), or the like. Wireless communication systems with high density nodes can exhibit higher system performance by cooperation between nodes. That is, if each node operates as an antenna or a group of antennas for one cell by receiving and receiving transmission and reception by one control station, each system can perform much better system performance than when each node operates as an independent base station without cooperating with each other. have. Hereinafter, a wireless communication system including a plurality of nodes and a base station for controlling the plurality of nodes is called a multi-node system.

An object and method for retrieving control information of a terminal in a multi-node system is provided.

According to an aspect of the present invention, a method for retrieving control information of a terminal includes location information of an E-PCFICH (physical control format indication channel) and a location of an E-control region through a physical downlink control channel (PDCCH) or an upper layer message from a base station Obtaining at least one of the information; Receiving an E-PCFICH based on the location information of the E-PCFICH; Obtaining size information of an E-control region through the E-PCFICH; And searching for an E-PDCCH in the E-control region, wherein the PDCCH is a control channel through which the base station transmits control information, and the first N (N is one of natural numbers of 1 to 4 or less) of a subframe. Transmitted in an orthogonal frequency division multiplexing (OFDM) symbol, the E-PDCCH is a control channel through which the base station transmits control information, and is located in at least one OFDM symbol next to the PDCCH in the subframe, The control region is a radio resource region including at least one of the E-PDCCH and the E-PCFICH, and is determined based on location information of the E-control region and size information of the E-control region.

The E-PCFICH region in which the E-PCFICH is transmitted and the E-PDCCH region in which the E-PDCCH is transmitted may be located in the same resource block.

The E-PCFICH may be transmitted in a resource region located outside the E-control region but not overlapping with the first OFDM symbol of the subframe to which the PCFICH for transmitting the size information of the PDCCH is allocated.

The size information of the E-control region may include at least one of size information in terms of time and size information in terms of frequency of the E-control region.

The size information on the time side of the E-control region may be given by the number of OFDM symbols or the number of slots, and the size information on the frequency side of the E-control region may be given by the number of resource blocks or the number of subcarriers.

The location information of the E-control region and the size information of the E-control region may be combined and then encoded into one piece of information.

At least one of the location information of the E-PCFICH and the location information of the E-control region may be included in downlink control information (DCI) or an upper layer message transmitted through the PDCCH.

At least one of the location information of the E-PCFICH and the location information of the E-control region is associated with node information received from the base station, and the node information includes a node index, a reference signal port number, a reference signal setting number, and a reference signal sub. It may include at least one of the frame setting number.

According to another aspect of the present invention, a method for retrieving control information of a terminal includes: obtaining location information of an E-control area through an upper layer message from a base station; Receiving an E-PCFICH at a predefined resource location; Acquiring size information of the E-control region through the E-PCFICH; And searching for an E-PDCCH in the E-control region, wherein the E-control region is a radio resource region including at least one of the E-PDCCH and the E-PCFICH. It is determined based on the location information and the size information of the E-control area.

The higher layer message may be a radio resource control (RRC) message.

The RRC message may be transmitted by being included in a master information block (MIB) included in a physical broadcast channel (PBCH) through which the base station broadcasts information.

The RRC message may be transmitted by being included in a physical downlink shared channel (PDSCH) through which the base station transmits information.

According to another aspect of the present invention, a method for retrieving control information of a terminal includes receiving a control format index (CFI) from a base station through a physical control format indication channel (PCFICH); Acquiring configuration information of an E-control area based on the control format index; And searching for an E-PDCCH in an E-control region determined based on the configuration information of the E-control region, wherein the PCFICH is size information of a physical downlink control channel (PDCCH) in which the base station transmits control information. It is a channel for transmitting the control format index, characterized in that the reserved index of the index specified by the size information of the physical downlink control channel (PDCCH).

The value of the control format index may be 4.

Terminal according to another aspect of the invention the RF unit for transmitting and receiving radio signals; And a processor coupled to the RF unit, wherein the processor acquires location information of a physical control format indication channel (E-PCFICH) and location information of an E-control region from a base station through a physical downlink control channel (PDCCH); Receiving the E-PCFICH based on the location information of the E-PCFICH, obtaining size information of an E-control region for at least one node of the plurality of nodes through the E-PCFICH, The E-PDCCH is searched for in the E-control region for the node, wherein the PDCCH is a control channel through which the base station transmits control information, and the first N (N is one of 1 or more natural numbers) of the subframes (orthogonal) frequency division multiplexing) symbol,

The E-control region for the at least one node is a radio resource region through which the at least one node transmits control information, and is determined based on the location information of the E-control region and the size information of the E-control region. It is characterized by.

Terminal according to another aspect of the invention the RF unit for transmitting and receiving radio signals; And a processor coupled to the RF unit, wherein the processor obtains location information of an E-control region for at least one node of a plurality of nodes through an upper layer message from a base station, and for the at least one node. Receive an E-PCFICH at a predefined resource location, obtain size information of an E-control area for the at least one node via the E-PCFICH, and E in the E-control area for the at least one node. Search for a PDCCH, wherein the E-control region for the at least one node is a radio resource region in which the at least one node transmits control information, the location information of the E-control region and the size of the E-control region; It is characterized by being determined based on the information.

Terminal according to another aspect of the invention the RF unit for transmitting and receiving radio signals; And a processor coupled to the RF unit, wherein the processor receives a control format index (CFI) from a base station through a physical control format indication channel (PCFICH), and receives a plurality of control format indexes based on the control format indexes. Acquiring configuration information of the E-control region for at least one node of the nodes, and searching the E-PDCCH in the E-control region for the at least one node determined based on the configuration information of the E-control region, The PCFICH is a channel through which the base station transmits size information of a physical downlink control channel (PDCCH) for transmitting control information, and the control format index is reserved among the indexes designated as the size information of the physical downlink control channel (PDCCH). It is an index.

According to the present invention, in a multi-node system, a node supports a resource region for transmitting control information to a terminal and a new channel for transmitting size information of the resource region. Even in a situation where the number of terminals supported by the node changes, control information can be transmitted efficiently.

1 shows an example of a multi-node system.

2 shows a structure of a radio frame in 3GPP LTE.

3 shows an example of a resource grid for one slot.

4 shows a structure of an uplink subframe.

5 shows a structure of a downlink subframe.

6 is a block diagram illustrating a generation process of a PDCCH.

7 shows an example of resource mapping of a PDCCH.

8 illustrates an example of a common search space and a terminal specific search space for monitoring a PDCCH.

9 shows an E-control area added according to an embodiment of the present invention.

10 shows an example in which an E-PCFICH region is allocated.

11 illustrates an example of an operation method of a terminal when an area in which E-control channels are transmitted is determined semi-statically.

12 illustrates an example of an operation method of a terminal when an area in which E-control channels are transmitted is dynamically determined.

13 is a block diagram illustrating a base station and a terminal.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various wireless communication systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA), or the like. IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e. UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is part of Evolved UMTS (E-UMTS) using Evolved-UMTS Terrestrial Radio Access (E-UTRA), which employs OFDMA in downlink and SC in uplink -FDMA is adopted. LTE-A (Advanced) is the evolution of 3GPP LTE.

For clarity, the description will be given on the assumption that it is applied to the LTE-A system, but the technical spirit of the present invention is not limited thereto.

1 shows an example of a multi-node system.

The multi-node system includes a base station (BS) and a plurality of nodes.

Base stations provide communication services for specific geographic areas. A base station generally refers to a fixed station communicating with a terminal, and may be referred to as other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), and an advanced base station (ABS).

1 illustrates a distributed antenna as an example of a node, and in this sense, a node may be referred to as an antenna node (AN). However, the node is not limited to a distributed antenna and may be implemented with, for example, a macro base station, a picocell base station (PeNB), a home base station (HeNB), a remote radio head (RRH), a repeater, and the like. Nodes are also called points. These nodes may be wired or wirelessly connected to the base station and controlled / managed by the base station.

The node may be identified or indicated through a reference signal (RS) or a pilot signal from the viewpoint of the terminal. The reference signal (or pilot signal, hereinafter identical) refers to a signal used by a transmitter and a receiver to be used for channel measurement and data demodulation. Examples of reference signals include a CSI-RS (channel status indication-reference signal) defined in 3GPP LTE-A, a preamble defined in IEEE 802.16m, a midamble, and the like. Such a reference signal or configuration of the reference signal may be mapped to each node (or a transmission antenna of each node). If the reference signal configuration and the mapping information between the node is given to the terminal or the terminal knows in advance, the terminal may identify or be instructed on the basis of the CSI-RS configuration, and may obtain channel state information on the node. The reference signal configuration may include information about a configuration index, the number of antenna ports of each node, a resource element used (RE), a transmission period, and an offset of a transmission time point. Therefore, for convenience of description, the description that the terminal measures a signal or generates channel state information for a specific node may mean that the terminal measures a signal for a specific reference signal or generates channel state information.

Referring back to FIG. 1, a node is connected to a base station via a wired / wireless network, and each node may be configured of one antenna or a plurality of antennas (ie, an antenna group). Antennas belonging to one node may be located within a few meters geographically and have the same characteristics. In a multi-node system, a node serves as an access point (AP) to which a terminal can access.

As described above, when a node consists of an antenna, such a multi-node system may be referred to as a distributed antenna system (DAS). In other words, a distributed antenna system refers to a system in which antennas (ie, nodes) are distributed in geographically diverse locations and managed by the base station. The distributed antenna system is different from that in the conventional centralized antenna system (CAS), antennas of a base station are concentrated and arranged in a cell center.

Here, the geographically distributed antennas may mean that when one receiver receives the same signal from a plurality of antennas, a channel state difference between each antenna and the receiver is arranged to be different by a specific value or more. have. Meaning that the antennas are concentrated may mean that the antennas are densely arranged such that the channel state difference between each antenna and one receiver is less than a specific value. The specific value may be variously determined according to a frequency, a service type, etc. used for the antennas.

In general, downlink means communication from a base station or a node to a terminal, and uplink means communication from a terminal to a base station or a node.

2 shows a structure of a radio frame in 3GPP LTE.

Referring to FIG. 2, a radio frame consists of 10 subframes, and one subframe consists of two slots. Slots in a radio frame are numbered with slots # 0 through # 19. The time taken for one subframe to be transmitted is called a Transmission Time Interval (TTI). TTI may be referred to as a scheduling unit for data transmission. For example, one radio frame may have a length of 10 ms, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms.

The structure of the radio frame is merely an example. Therefore, the number of subframes included in the radio frame or the number of slots included in the subframe may be variously changed.

3 shows an example of a resource grid for one slot.

Slots include a downlink slot and an uplink slot. The downlink slot includes a plurality of OFDM symbols in the time domain and includes N _RB resource blocks (RBs) in the frequency domain. The OFDM symbol may be referred to as an SC-FDMA symbol according to a transmission scheme. The RB includes one slot in the time domain and a plurality of consecutive subcarriers in the frequency domain in resource allocation units.

The number N _RB of resource blocks included in the downlink slot depends on a downlink transmission bandwidth set in a cell. For example, in the LTE system, N _RB may be any one of 6 to 110. The structure of the uplink slot may also be the same as that of the downlink slot.

Each element on the resource grid is called a resource element (RE). Resource elements on the resource grid may be identified by an index pair (k, l) in the slot. Where k (k = 0, ..., N _RB × 12-1) is the subcarrier index in the frequency domain, and l (l = 0, ..., 6) is the OFDM symbol index in the time domain.

One resource block includes 7 OFDM symbols in the time domain and 12 subcarriers in the frequency domain to include 7 × 12 resource elements, but the number of OFDM symbols and the number of subcarriers in the resource block is limited thereto. It is not. The number of OFDM symbols and the number of subcarriers can be variously changed according to the length of the CP, frequency spacing, and the like. For example, the number of OFDM symbols is 7 for a normal CP and the number of OFDM symbols is 6 for an extended CP. The number of subcarriers in one OFDM symbol may be selected and used among 128, 256, 512, 1024, 1536 and 2048.

4 shows a structure of an uplink subframe.

The uplink subframe may be divided into a control region and a data region in the frequency domain. The control region is allocated a physical uplink control channel (PUCCH) for transmitting uplink control information. The data region is allocated a physical uplink shared channel (PUSCH) for transmitting data. The UE may not simultaneously transmit or simultaneously transmit PUCCH and PUSCH according to configuration.

PUCCH for one UE is allocated to an RB pair in a subframe. Resource blocks belonging to a resource block pair occupy different subcarriers in each of a first slot and a second slot. The frequency occupied by RBs belonging to the RB pair allocated to the PUCCH is changed based on a slot boundary. This is called that the RB pair allocated to the PUCCH is frequency-hopped at the slot boundary. The UE may obtain frequency diversity gain by transmitting uplink control information through different subcarriers over time.

The uplink control information transmitted on the PUCCH includes a hybrid automatic repeat request (HARQ) acknowledgment (ACK) / non-acknowledgement (NACK), channel state information (CSI) indicating a downlink channel state, and an uplink radio resource allocation request. (Scheduling Request). The CSI includes a precoding matrix index (PMI) indicating a precoding matrix, a rank indicator (RI) indicating a rank value preferred by the UE, a channel quality indicator (CQI) indicating a channel state, and the like.

PUSCH is mapped to an uplink shared channel (UL-SCH) which is a transport channel. The uplink data transmitted on the PUSCH may be a transport block which is a data block for the UL-SCH transmitted during the TTI. The transport block may be user information. Alternatively, the uplink data may be multiplexed data. The multiplexed data may be a multiplexed transport block and control information for the UL-SCH. For example, control information multiplexed with data may include CQI, PMI, HARQ ACK / NACK, RI, and the like. Alternatively, the uplink data may consist of control information only.

5 shows a structure of a downlink subframe.

The downlink subframe includes two slots in the time domain, and each slot includes seven OFDM symbols in the normal CP. The leading up to 3 OFDM symbols (up to 4 OFDM symbols for 1.4Mhz bandwidth) of the first slot in the subframe are the control regions to which control channels are assigned, and the remaining OFDM symbols are the Physical Downlink Shared Channel (PDSCH). Becomes the data area to be allocated. PDSCH refers to a channel through which a base station or node transmits data to a terminal.

Control channels transmitted in the control region include a Physical Control Format Indicator Channel (PCFICH), a Physical Hybrid-ARQ Indicator Channel (PHICH), and a Physical Downlink Control Channel (PDCCH).

The PCFICH transmitted in the first OFDM symbol of the subframe carries a control format indicator (CFI), which is information about the number of OFDM symbols (that is, the size of the control region) used for transmission of control channels in the subframe. The terminal first receives the CFI on the PCFICH, and then monitors the PDCCH. Unlike the PDCCH, the PCFICH does not use blind decoding and is transmitted on a fixed PCFICH resource of a subframe.

The PHICH carries a positive-acknowledgement (ACK) / negative-acknowledgement (ACK) signal for an uplink hybrid automatic repeat request (HARQ). The ACK / NACK signal for UL (uplink) data on the PUSCH transmitted by the UE is transmitted on the PHICH.

Control information transmitted through the PDCCH is called downlink control information (DCI). DCI is a resource allocation of PDSCH (also called DL grant), a PUSCH resource allocation (also called UL grant), a set of transmit power control commands for individual UEs in any UE group. And / or activation of Voice over Internet Protocol (VoIP).

6 is a block diagram illustrating a generation process of a PDCCH.

The base station determines the PDCCH format according to the DCI to be sent to the terminal, attaches a cyclic redundancy check (CRC) to the DCI, and unique identifier according to the owner or purpose of the PDCCH (this is called a Radio Network Temporary Identifier) Mask the CRC (510).

The following table shows the types of RNTI.

RNTI Usage Transport Channel Logical Channel P-RNTI Paging and System Information change notification PCH PCCH SI-RNTI Broadcast of System Information DL-SCH BCCH M-RNTI MCCH Information change notification N / A N / A RA-RNTI Random Access Response DL-SCH N / A Temporary C-RNTI Competitive resolution, when no valid C-RNTI is available. (Contention Resolution (when no valid C-RNTI is available)) DL-SCH CCCH Temporary C-RNTI Msg3 transmission UL-SCH CCCH, DCCH, DTCH C-RNTI Dynamically scheduled unicast transmission UL-SCH DCCH, DTCH C-RNTI Dynamically scheduled unicast transmission DL-SCH CCCH, DCCH, DTCH C-RNTI Triggering of PDCCH ordered random access N / A N / A Semi-Persistent Scheduling C-RNTI Semi-Persistently Scheduled Unicast Transmission, Activation, Reactivation, and Retransmission
(activation, reactivation and retransmission)) DL-SCH, UL-SCH DCCH, DTCH Semi-Persistent Scheduling C-RNTI Semi-Persistently scheduled unicast transmission
(deactivation)) N / A N / A TPC-PUCCH-RNTI Physical layer uplink power control N / A N / A TPC-PUSCH-RNTI Physical layer uplink power control N / A N / A

Table 2 below shows the range of values of the RNTI.

Value (hexadecimal) RNTI 0000 N / A 0001-003C RA-RNTI, C-RNTI, Semi-Persistent Scheduling C-RNTI, Temporary C-RNTI, TPC-PUCCH-RNTI and TPC-PUSCH-RNTI (see note) 003D-FFF3 C-RNTI, Semi-Persistent Scheduling C-RNTI, Temporary C-RNTI, TPC-PUCCH-RNTI and TPC-PUSCH-RNTI FFF4-FFFC Reserved for future use FFFD M-RNTI FFFE P-RNTI FFFF SI-RNTI

If the PDCCH is for a specific terminal, a unique identifier of the terminal, for example, a C-RNTI (Cell-RNTI) may be masked to the CRC. Alternatively, if the PDCCH is for a paging message, a paging indication identifier, for example, P-RNTI (P-RNTI), may be masked to the CRC. If it is a PDCCH for system information, a system information identifier and a system information-RNTI (SI-RNTI) may be masked to the CRC. A random access-RNTI (RA-RNTI) may be masked to the CRC to indicate a random access response that is a response to the transmission of the random access preamble of the UE.

If the C-RNTI is used, the PDCCH carries control information for the corresponding specific UE (called UE-specific control information), and if another RNTI is used, the PDCCH is shared by all or a plurality of terminals in the cell. (common) carries control information.

The DCC added with the CRC is encoded to generate coded data (520). Encoding includes channel encoding and rate matching.

The coded data is modulated to generate modulation symbols (530).

The modulation symbols are mapped to a physical resource element (RE) (540). Each modulation symbol is mapped to an RE.

7 shows an example of resource mapping of a PDCCH.

In FIG. 7, R0 represents a reference signal of the first antenna port, R1 represents a reference signal of the second antenna port, R2 represents a reference signal of the third antenna port, and R3 represents a reference signal of the fourth antenna port.

The control region in the subframe includes a plurality of control channel elements (CCEs). The CCE is a logical allocation unit used to provide a coding rate according to the state of a radio channel to a PDCCH and corresponds to a plurality of resource element groups (REGs). The format of the PDCCH and the number of bits of the PDCCH are determined according to the correlation between the number of CCEs and the coding rate provided by the CCEs.

One REG (denoted as quadruplet in the figure) contains four REs and one CCE contains nine REGs. {1, 2, 4, 8} CCEs may be used to configure one PDCCH, and each element of {1, 2, 4, 8} is called a CCE aggregation level.

That is, the PDCCH is composed of one or more CCEs and is mapped to a physical resource after performing interleaving of REG units and performing a cyclic shift based on a cell ID.

A plurality of PDCCHs may be transmitted in one subframe. The UE monitors the plurality of PDCCHs in every subframe. Here, monitoring refers to the terminal attempting to decode or detect the PDCCH according to the PDCCH format.

In 3GPP LTE, blind decoding is used to detect the PDCCH. Blind decoding is also referred to as blind detection. Blind decoding is a method of demasking a desired identifier in a CRC of a received PDCCH (which is called a candidatetae PDCCH) and checking a CRC error to determine whether the corresponding PDCCH is its control channel. Since the UE does not know which CCE aggregation level or DCI format is transmitted at which position in the control region, the UE performs such blind decoding.

In 3GPP LTE, a search space (SS) is used to reduce the burden of blind decoding. The search space may be referred to as a monitoring set of the CCE for the PDCCH. The UE monitors the PDCCH in the corresponding search space.

8 illustrates an example of a common search space and a terminal specific search space for monitoring a PDCCH.

The search space is divided into a common search space (CSS) and a UE-specific search space (USS). The common search space is a space for searching for a PDCCH having common control information (sometimes referred to as cell specific control information). The common search space may be configured with 16 CCEs from CCE indexes 0 to 15, and has a CCE aggregation level of {4, 8}. Support PDCCH with However, PDCCHs (DCI formats 0 and 1A) carrying UE specific information may also be transmitted in the common search space. The UE-specific search space supports a PDCCH having a CCE aggregation level of {1, 2, 4, 8}.

Now, a signal transmission method in a multi-node system will be described. Hereinafter, an example in which the present invention is mainly applied to a multi-node system will be described, but is not limited thereto. That is, it can be applied to any wireless communication system that is not a multi-node system.

In a multi-node system, a base station having a high transmit power and a node having a low transmit power may be arranged. In order to support more terminals through limited radio resources, a new signal transmission method is required. In particular, it is a question of how to allocate the control region to transmit the control signal to the terminal.

1. E-control area.

9 shows an E-control area added according to an embodiment of the present invention.

Referring to FIG. 9, the E-control region may be located after the existing control region in the time domain. For example, if an existing control region is transmitted in the first three OFDM symbols of a subframe, an E-control region may be added to OFDM symbols located after the three OFDM symbols. In the frequency domain, the existing control region and the E-control region may coincide or may be set differently. 9 shows an example in which the E-control region is set only in some frequency bands of the existing control region.

Here, the E-control region may mean a radio resource region capable of transmitting different control information for each node of the multi-node system. In this sense, the E-control region may be referred to as an 'RRH control region'.

In the E-control region, a signal for an advanced UE may be transmitted. The improved terminal means a terminal capable of transmitting and receiving signals according to the present invention. The existing terminal means a terminal operating by the current communication standard. In other words, the existing terminal may be a first type terminal operated by a first radio access technology (RAT), for example, 3GPP LTE Rel-10, and the improved terminal may be a second RAT, for example, It may be a second type terminal operated by 3GPP LTE Rel-11. Here, the second RAT may be evolution of the first RAT.

In the E-control area, for example, a control channel for an improved terminal can be transmitted. The control channel for the improved terminal is called an E-control channel to distinguish it from the control channel for the existing terminal. E-control channels include E-PDCCH, E-PCFICH, E-PHICH and the like. Hereinafter, PDCCH, PCFICH, and PHICH mean an existing control channel, and E-PDCCH, E-PCFICH, and E-PHICH mean an E-control channel according to the present invention. In addition, the X region refers to a radio resource region in which an X channel is transmitted from a base station or a node, and a radio resource region receiving an X channel from a terminal. For example, the E-PDCCH region means a radio resource region in which the E-PDCCH is transmitted.

In addition, in the E-control region, a reference signal not used by the existing terminal may be used. The improved terminal may receive a signal using a reference signal not used by the existing terminal in the E-control region.

The E-control region may be set to be the same as the R-PDCCH region used by the base station to transmit control information to the relay station in view of the allocated resource region. The R-PDCCH region may be set for each slot as shown in the following table.

Settings
(Configuration) ‘DL-StartSymbol’ Last symbol index
(End symbol index) 0 One 6 One 2 6 2 3 6

Settings
(Configuration) Starting symbol index
(Start symbol index) Last symbol index
(End symbol index) 0 0 6 One 0 5

Table 3 shows the R-PDCCH configuration for the first slot, and Table 4 shows the R-PDCCH configuration for the second slot. The base station gives the "DL-StartSymbol" parameter of Table 3 through the higher layer signal. When the base station and the relay station transmit the downlink subframe time-aligned to the subframe boundary, configuration 1 of Table 4 is used, otherwise configuration 0 of Table 4 is used. That is, the R-PDCCH is from the OFDM symbol of the first slot indicated by the "DL-StartSymbol" parameter to the OFDM symbol # 6 or # 5 of the second slot. The E-control region may be set equal to this R-PDCCH region. For example, when there is no relay station in the multi-node system, the same resource region as the R-PDCCH region may be set as the E-control region.

The E-control region and the R-PDCCH region differ in terms of their purpose and transmitted control channel. That is, the R-PDCCH region is used for the base station for transmitting control information to the relay station, and the E-control region is used for the base station or node for the purpose of transmitting control information to the terminal. The control information transmitted in the E-control region is ultimately information to be received by the terminal and may include cell specific control information (eg, system information), terminal specific control information, and node specific control information.

In terms of the control channel, only the R-PDCCH is transmitted in the R-PDCCH region, whereas E-PDCCH, E-PCFICH, and E-PHICH may be transmitted in the E-control region.

2. Signaling presence, location information, size information of E-control area.

1) The base station 1. through the upper layer information, existing physical channels (for example, PBCH, PDSCH, PDCCH), or E-PCFICH 1. presence or absence of the E-control area, 2. location information of the E-control area, 3 4. Size information on the time side of the E-control region, and 4. Size information on the frequency side of the E-control region. Here, the size information in terms of time may be given as the number of OFDM symbols or the number of slots, and the size information in the frequency domain may be given as the number of resource blocks or the number of subcarriers. Location information of the E-control area may be referred to as scheduling information. That is, the terminal may know the reference time point and the reference frequency at which the E-control region is transmitted by the location information of the E-control region. For example, the position information of the E-control region may indicate which subframe is transmitted and the start frequency of the E-control region.

The information 1 to 4 may be separately encoded and transmitted, or two or more pieces of information may be combined and then encoded and transmitted as one piece of information (ie, may be transmitted after being jointly encoded). In this case, a predetermined table may be used between the base station and the terminal.

The following table shows an example of E-PDCCH configuration information that can be used when joint encoding of some of the above four information is transmitted.

E-PDCCH setting information Resource Block Count E-PDCCH Location 0 0 Not available (N / A) One One 1 resource block of the center frequency
(RB at the center frequency) 2 One 1 resource block of lowest frequency
(Lowest RB) 3 2 2 resource blocks of center frequency
(RBs at the center frequency) 4 2 2 resource blocks of lowest frequency and highest frequency
(Lowest and highest PRB)

In Table 5, when the E-PDCCH configuration information is '0', it indicates that the E-PDCCH does not exist. When the E-PDCCH configuration information is '1', the E-PDCCH exists, and the size of the E-PDCCH in the frequency domain informs two pieces of information, that is, one resource block located at the center frequency of the set band. If the E-PDCCH configuration information is '2', the E-PDCCH exists, and the size of the E-PDCCH in the frequency domain indicates two pieces of information, that is, one resource block of the lowest frequency in the set band. When the E-PDCCH configuration information is '3', the E-PDCCH exists, and the size of the E-PDCCH in the frequency domain informs two pieces of information, two resource blocks located at the center frequency of the set band. If the E-PDCCH configuration information is '4', there is an E-PDCCH, and the size of the E-PDCCH in the frequency domain indicates two pieces of information, two resource blocks of the lowest frequency and the highest frequency in the set band. Of course, Table 5 is only an example.

2) The base station (or node) may inform the UE of the existence and / or allocation location of the E-control region through the CFI value transmitted through the existing PCFICH.

The following table shows the CFI index and CFI codewords defined in the current standard.

CFI CFI Codeword
<b0, b1, ... , b31> One <0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0 , 1,1,0,1,1,0,1> 2 <1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1 , 0,1,1,0,1,1,0> 3 <1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1 , 1,0,1,1,0,1,1> 4 (reserved)
(Reserved) <0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 , 0,0,0,0,0,0,0>

As shown in Table 6 above, CFI index 4 is a reserved index. The reserved CFI index may be used to indicate whether an E-control region exists or a setting of the E-control region in a corresponding subframe. The setting of the E-control area means the size and position of the E-control area.

For example, when the CFI index is 4, the number of OFDM symbols in the PDCCH region may be 3, indicating that an E-control region exists. When the terminal receives the CFI index 4 through the PCFICH, it can be seen that the E-control region exists. In addition, it can be seen that the PDCCH exists in three OFDM symbols of a subframe, and the E-control region is located from the last OFDM symbol or the last to the second OFDM symbol of the subframe after the three OFDM symbols. Here, the number of OFDM symbols of the PDCCH is only three examples.

If the CFI index is 4, existing terminals may not recognize this and may cause an operation error. Therefore, the resource area that is not used by the existing terminal, for example, can be limited to use only in a carrier that is not accessible to the existing terminal.

3.E-physical control format indication channel (E-PCFICH)

 Unlike the R-PDCCH region, the E-control region may change dynamically. Since the R-PDCCH region is used to transmit control information to a fixed number of relay stations, its size does not change dynamically. On the other hand, the E-control area is used to transmit control information for terminals existing in the coverage of the node, and the size of the terminal can be changed dynamically because the number of terminals existing in the coverage of the node can be changed. Therefore, information informing the size of the E-control area is required.

In order for the terminal to recognize the E-control region, location information and size information of the E-control region may be needed. For example, the subframe and the reference frequency band through which the E-control region is transmitted can be known through the location information of the E-control region. Then, the size information of the E-control region shows the size of the E-control region in terms of time (ie, how many OFDM symbols) and the size of frequency (ie, how many resource blocks). Can be seen. The channel for transmitting the size information of the E-control area will be referred to as E-PCFICH hereinafter.

The E-PCFICH may be defined so as not to overlap with the area where the existing PCFICH is transmitted. That is, the E-PCFICH may be defined to be transmitted in an OFDM symbol other than the first OFDM symbol of the subframe.

The E-PCFICH region in which the E-PCFICH is transmitted may be independently located in the E-control region. Alternatively, the E-PCFICH may be included in the E-control region or the position may be determined depending on the E-control region.

10 shows an example in which an E-PCFICH region is allocated.

Referring to FIG. 10A, E-PCFICH regions 701 and 702 corresponding to E-control regions for each node are allocated. That is, the E-PCFICH 701 corresponding to the E-control region for the node #n and the E-PCFICH 702 corresponding to the E-control region for the node # (n + 1) are allocated, respectively.

Referring to FIG. 10B, unlike FIG. 10A, an E-control region for each node does not exist and may be given as a common radio resource region. In this case, the size information of the common radio resource region may be provided to the terminal through one E-PCFICH 703 for the E-control regions for the plurality of nodes.

Although the signaling overhead of the method of FIG. 10 (a) is relatively large compared to the method of FIG. 10 (b), there is an advantage in that the size of the E-PDCCH can be flexibly changed according to the change in the number of terminals controlled for each node. The method of FIG. 10B has advantages and disadvantages opposite to that of FIG. 10A.

In FIG. 10, the E-PCFICH regions 701, 702, and 703 exist in the E-control region. However, this is not a limitation and may exist outside the E-control region.

The following describes which resource region control channels can be transmitted in the E-control region. As described above, the control channels in the E-control region include E-PHICH, E-PDCCH, E-PCFICH, etc. These control channels are referred to as E-control channels for convenience.

First, an area in which E-control channels are transmitted may be determined statically for each node. The terminal may receive the index of the node, the cell ID, the total number of nodes in the cell, the system band (the number of resource blocks) and the like from the base station. Here, the index of the node may be a reference signal index divided for each node. The reference signal index may include a reference signal port number, a reference signal configuration number, and a reference signal subframe configuration number. Such information may be included in system information transmitted by a base station, included in higher layer information, or included in a synchronization signal.

The area in which the E-control channel is transmitted may be defined as a function of some or all of the above-described cell ID, node index, total number of nodes in the cell, and system band (number of resource blocks). Then, the base station transmits information such as cell ID, node index, etc. without the need for a separate signaling to inform the UE of the region in which the E-control channel is transmitted. The control channel can be transmitted. The UE can know the area where the E-control channel is transmitted through information such as a cell ID and a node index.

Alternatively, the region in which the E-control channels are transmitted may be determined semi-statically. For example, the E-PCFICH exists at a predefined location, and the location information of the E-PDCCH may be included in the higher layer signal and transmitted.

11 illustrates an example of an operation method of a terminal when an area in which E-control channels are transmitted is determined semi-statically.

Referring to FIG. 11, the terminal acquires location information of the E-control area through an upper layer message (S401). The higher layer message may be, for example, an RRC message transmitted by the base station, and location information of the E-control area may be included in the RRC message. The RRC message may be included in a system information block (SIB) transmitted in a PDSCH or in a master information block (MIB) transmitted in a PBCH. Alternatively, the location information of the E-control area may be included in the RRC information element (IE) other than the SIB or MIB and transmitted. The location information of the E-control area may be transmitted through a newly defined RRC message for the UE added or improved in the existing RRC message.

The terminal receives the E-PCFICH at the prescribed resource location to obtain size information of the E-control area (S402).

The UE searches for the E-PDCCH through blind decoding in the E-control region (S403).

Alternatively, the region in which the E-control channels are transmitted may be determined dynamically. That is, the base station may add the presence and / or location information of the E-control channel to the DCI transmitted through the existing PDCCH and transmit. Then, the UE can obtain the presence and location information of the E-control channel through the existing PDCCH. The E-PCFICH and the E-PDCCH may be defined to be located in the same resource block. In this case, the UE may receive the resource block start position of the E-PCFICH or the E-PDCCH through the existing PDCCH.

12 illustrates an example of an operation method of a terminal when an area in which E-control channels are transmitted is dynamically determined.

Referring to FIG. 12, the terminal acquires location information of the E-PCFICH and the E-control region through the existing PDCCH (S301). For example, location information of the E-PCFICH may be added to the DCI transmitted through the existing PDCCH.

The terminal receives the E-PCFICH based on the location information of the E-PCFICH to obtain size information of the E-control area (S302). The size information of the E-control region may be given by the number of OFDM symbols in terms of time, the number of resource blocks or the number of subcarriers in frequency.

The UE searches for the E-PDCCH through blind decoding in the E-control region (S303).

If there are a plurality of E-PCFICHs and E-control regions for a plurality of nodes, the operations described with reference to FIGS. 11 and 12 may be defined for the E-PCFICH and E-control regions for a particular node. Accordingly, for the operation, the base station may additionally provide the terminal with information on which E-control area of the plurality of E-control areas should receive control information.

13 is a block diagram illustrating a base station and a terminal.

The base station 100 includes a processor 110, a memory 120, and an RF unit 130. The processor 110 implements the proposed functions, processes and / or methods. For example, the processor 110 may transmit information on the existence of the E-control area, the location information of the E-control area, the size information in terms of time of the E-control area, and the E- through the existing physical channel or the R-PCFICH. The size information on the frequency side of the control region may be transmitted as an upper layer message such as an RRC message or a physical layer signal such as DCI or CFI. The memory 120 is connected to the processor 110 and stores various information for driving the processor 110. The RF unit 130 is connected to the processor 110 and transmits and / or receives a radio signal.

The terminal 200 includes a processor 210, a memory 220, and an RF unit 230. The processor 210 implements the proposed functions, processes and / or methods. For example, the processor 210 may include the existence of an E-control region transmitted by a base station through an existing physical channel or an E-PCFICH, location information of the E-control region, size information in terms of time of the E-control region, Receive size information on the frequency side of the E-control region. Then, the E-PDCCH is searched for in the E-control area. The memory 220 is connected to the processor 210 and stores various information for driving the processor 210. The RF unit 230 is connected to the processor 210 to transmit and / or receive a radio signal.

Processors 110 and 210 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, data processing devices, and / or converters for interconverting baseband signals and wireless signals. The OFDM transmitter and OFDM receiver of FIG. 7 may be implemented within processors 110 and 210. The memory 120, 220 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage device. The RF unit 130 and 230 may include one or more antennas for transmitting and / or receiving a radio signal. When the embodiment is implemented in software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in the memories 120 and 220 and executed by the processors 110 and 210. The memories 120 and 220 may be inside or outside the processors 110 and 210, and may be connected to the processors 110 and 210 by various well-known means.

Although the present invention has been described above with reference to the embodiments, it will be apparent to those skilled in the art that the present invention may be modified and changed in various ways without departing from the spirit and scope of the present invention. I can understand. Therefore, the present invention is not limited to the above-described embodiment, and the present invention will include all embodiments within the scope of the following claims.

Claims (17)

In the control information retrieval method of the terminal,
Obtaining at least one of position information of a physical control format indication channel (E-PCFICH) and position information of an E-control region through a physical downlink control channel (PDCCH) or an upper layer message from a base station;
Receiving an E-PCFICH based on the location information of the E-PCFICH;
Obtaining size information of an E-control region through the E-PCFICH; And
Searching for the E-PDCCH in the E-control region;
The PDCCH is a control channel through which the base station transmits control information, and is transmitted in first N (orthogonal frequency division multiplexing) OFDM symbols (N is one of 1 or more natural numbers) of a subframe,
The E-PDCCH is a control channel through which the base station transmits control information and is located in at least one OFDM symbol next to the PDCCH in the subframe.
The E-control region is a radio resource region including at least one of the E-PDCCH and the E-PCFICH and is determined based on location information of the E-control region and size information of the E-control region. How to. The method of claim 1,
The E-PCFICH region in which the E-PCFICH is transmitted and the E-PDCCH region in which the E-PDCCH is transmitted are located in the same resource block. 2. The method of claim 1, wherein the E-PCFICH is located outside the E-control region, and is transmitted in a resource region not overlapping with the first OFDM symbol of the subframe to which the PCFICH transmitting the size information of the PDCCH is allocated. How to. The method of claim 1, wherein the size information of the E-control region includes at least one of size information on a time side and size information on a frequency side of the E-control region. 5. The method of claim 4, wherein the size information on the time side of the E-control region is given by the number of OFDM symbols or the number of slots, and the size information on the frequency side of the E-control region is the number of resource blocks or the number of subcarriers. Given by. 5. The method of claim 4, wherein the position information of the E-control region and the size information of the E-control region are combined and composed of one information and then encoded. The method of claim 1, wherein at least one of the location information of the E-PCFICH and the location information of the E-control region is included in a downlink control information (DCI) or an upper layer message transmitted through the PDCCH. How to feature. The method of claim 1, wherein at least one of the location information of the E-PCFICH and the location information of the E-control region is associated with node information received from the base station.
Wherein the node information includes at least one of a node index, a reference signal port number, a reference signal configuration number, and a reference signal subframe configuration number. In the control information retrieval method of the terminal,
Obtaining location information of the E-control area from the base station through a higher layer message;
Receiving an E-PCFICH at a predefined resource location;
Acquiring size information of the E-control region through the E-PCFICH; And
Searching for the E-PDCCH in the E-control region;
The E-control region is a radio resource region including at least one of the E-PDCCH and the E-PCFICH and is determined based on location information of the E-control region and size information of the E-control region. How to. 10. The method of claim 9, wherein the higher layer message is a radio resource control (RRC) message. The method of claim 10, wherein the RRC message is transmitted in a manner of being included in a master information block (MIB) included in a physical broadcast channel (PBCH) through which the base station broadcasts information. The method of claim 10, wherein the RRC message is included in a physical downlink shared channel (PDSCH) in which the base station transmits information. In the control information retrieval method of the terminal,
Receiving a control format index (CFI) from a base station through a physical control format indication channel (PCFICH);
Acquiring configuration information of an E-control area based on the control format index; And
Searching for the E-PDCCH in the E-control region determined based on the configuration information of the E-control region,
The PCFICH is a channel through which the base station transmits size information of a physical downlink control channel (PDCCH) for transmitting control information, and the control format index is reserved among the indexes designated as the size information of the physical downlink control channel (PDCCH). And an index. 14. The method of claim 13, wherein the value of the control format index is four. RF unit for transmitting and receiving a radio signal; And
A processor connected to the RF unit, wherein the processor
Obtaining location information of E-PCFICH (Physical Control Format Indication Channel) and location information of E-control area from the base station through physical downlink control channel (PDCCH), and based on location information of E-PCFICH, E-PCFICH is obtained. Receive, obtain the size information of the E-control region for at least one node of the plurality of nodes through the E-PCFICH, and search for the E-PDCCH in the E-control region for the at least one node,
The PDCCH is a control channel through which the base station transmits control information, and is transmitted in first N (orthogonal frequency division multiplexing) OFDM symbols (N is one of 1 or more natural numbers) of a subframe,
The E-control region for the at least one node is a radio resource region through which the at least one node transmits control information, and is determined based on the location information of the E-control region and the size information of the E-control region. Terminal, characterized in that. RF unit for transmitting and receiving a radio signal; And
A processor connected to the RF unit, wherein the processor
Obtain location information of an E-control area for at least one node of a plurality of nodes through an upper layer message from a base station, receive an E-PCFICH at a predefined resource location for the at least one node, and Acquire size information of the E-control region for the at least one node through PCFICH and search for the E-PDCCH in the E-control region for the at least one node;
The E-control region for the at least one node is a radio resource region through which the at least one node transmits control information, and is determined based on the location information of the E-control region and the size information of the E-control region. Terminal, characterized in that. RF unit for transmitting and receiving a radio signal; And
A processor connected to the RF unit, wherein the processor
Receives a control format index (CFI) from a base station through a physical control format indication channel (PCFICH), and setup information of an E-control area for at least one node of a plurality of nodes based on the control format index. Acquire the E-PDCCH in the E-control region for the at least one node determined based on the configuration information of the E-control region,
The PCFICH is a channel through which the base station transmits size information of a physical downlink control channel (PDCCH) for transmitting control information, and the control format index is reserved among the indexes designated as the size information of the physical downlink control channel (PDCCH). Terminal, characterized in that the index.

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